It is often desirable to connect two surfaces securely together without producing a permanent bond. It also may be desirable to attach and subsequently detach these surfaces several times. A fastening device attaches two surfaces that are in contact with each other until a separating force is applied. A refastening fastening device allows the two surfaces to have repeated cycles of attachment and detachment.
One type of refastenable fastening device involves a male and female component. The male component, referred to herein as the hook component, is a fabric having a plurality of resilient, upstanding hook-shaped elements. The female component, referred to herein as the loop component, is a fabric having a plurality of upstanding loops. When the surfaces of the hook and loop components are pressed together, they become entangled. This creates a mechanical bond which will not disengage under normal conditions. The bond is held secure because it is difficult to break all of the bonds between the hooks and loops at one time. A gradual peeling force, however, releases the hooks from the loops and opens the fastener. As the peeling force is applied, the hooks, made of a resilient material, straighten and become disentangled from the loops of the loop component. The hooks and the loops are not destroyed by this separation and therefore can be reattached by again placing the hook and loop components in a face-to-face relationship.
Such hook and loop refastenable fastening devices are well known in the art and described in U.S. Pat. Nos. 2,717,437 and 3,009,235, the contents of which are incorporated herein in their entirety. These refastening fastening devices are commonly sold under the trademark "Velcro."
The loop component performs several functions in the mechanical bond formed in a refastening fastening device. For example, the loop component provides an entanglement area for the hooks to become attached. This area is where the mechanical bond is formed. The loop component also provides a space for the hooks. to remain while the fastener is closed.
The loop component is intended to engage and disengage the hook component several times during normal use. Just as the hooks of the hook component have a degree of resiliency to allow repeated use, the resiliency of the loops provides a degree of structural integrity allowing the loops to remain dimensionally stable during repeated use. After the components are separated, enough loops remain undamaged for reattachment to the hook component.
Hook and loop refastening fastening devices are useful for disposable articles, for example in disposable diapers. However, their use has been limited due to the expense of the components. Conventional hook and loop components are typically made by weaving or knitting resilient yarn materials into a loop structure, and then cutting the loops when a hook structure is desired. Thus, these woven or knitted hook and loop components are systematic. The position of each yarn producing a loop is carefully determined before the fabric is produced. Such detailed manufacturing steps are often time consuming and expensive.
U.S. Pat. No. 3,694,867 issued to Stumpf discloses a loop component made with a "high loft" fabric attached to a backing layer. Fibers are mechanically manipulated to form the loops and are attached to the backing layer. These manufacturing steps add to the cost of the final loop component.
U.S. Pat. No. 4,739,635 to Conley relates to a loop component produced by feeding a backing layer into a knit stitch machine, where loops are knit into the backing layer at predetermined intervals. Example 5 of Conley shows that knitting without the backing layer resulted in a product lacking sufficient strength and stability to securely engage the hook component. The knitting steps are also complex and time consuming.
U.S. Pat. No. 4,600,618 to Raychock relates to a splint material with a hook and loop fastening device, where the loop component comprises needlepunched fibers. The Raychock patent, however, does not present any examples of the needlepunch fabric, and does not provide any details about the properties and characteristics of the loop component.
Accordingly, there exists a need for a low-cost refastening fastening loop component with high performance properties. Such a loop component should have an adequate range of caliper, weight, opacity, and peel strength. Preferably, the loops Withstand repeated cycles of attachment and detachment to the hook component.
Further, as disposable articles having hook and loop devices may be stored and/or sold under compression, a need exists for a loop component with favorable performance properties after such compression has been released.